LINGUAL NERVE PARESTHESIA - PowerPoint Presentation

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LINGUAL NERVE PARESTHESIA

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SYNOPSIS

INTRODUCTION

NERVE INJURIESANATOMY OF LINGUAL NERVEFUNCTIONS OF LINGUAL NERVELINGUAL NERVE INJURYETIOLOGY

PATHOPHYSIOLOGYPREDISPOSING FACTORSSIGNS AND SYMPTOMSEXAMINATIONDIAGNOSIS-IMAGING

TREATMENT OF LINGUAL NERVE INJURIES

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INTRODUCTION:

Lingual nerve – A branch of

mandibular division of trigeminal nerve supplying the anterior two third of tongue.Paresthesia – An abnormal sensation such as tingling , tickling , pricking , numbness of a person’s skin with no apparent physical cause.

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NERVE INJURIES

Three types:

NEUROPRAXIA- (demyelination) reversible conduction block AXONOTMESIS- (demyelination + axon loss) endoneurium

intact. NEUROTOMESIS- most severe as axonotmesis + involvement of endoneurium

, epineurium and perineurium.

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ANATOMY OF LINGUAL NERVE

The lingual nerve may be round , oval or flat varies from 1.53mm to 4.5 mm

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Mandibular

nerve pathway

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Passes medially to lateral

pterygoid muscle.The nerve lies parallel to the inferior alveolar nerve but medial and anterior to it.

Then, passes deep to reach the side of the base of the tongue and lies below the lateral lingual sulcus.Has communications with the chorda

tympani of facial nerve.Finally runs , crossing the duct of submandibular gland and along the tongue to its tip becoming the sublingual nerve

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Functions of lingual nerve:

The nerve supplies general somatic afferent

innervation from the mucous membrane if anterior two third of tongue.It also carries nerve fibers that are not part of trigeminal nerve(chorda

tympani) which provides special sensation to anterior two third of tongue as well as sympathetic and parasympathetic.

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LINGUAL NERVE INJURY

The most common nerve injury which cause sensory disturbance in the

inerveted area.ANATOMICAL RELATIONSHIP: The lingual nerve courses from a more lateral to medial position as it approaches the mandibular third molar.

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PATHOPHYSIOLOGY OF NERVE INJURY

SEGMENTAL DEMYELINATION- it is the selective dissolution of the myelin sheath segment & is characterized by slowing of conduction velocity, associated with minor

neuropraxia injury of axons.NEUROTROPHIC EFFECT- if the tissue deinnervated for a long

time,certain clinical changes take place.

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ETIOLOGY

1.In case of removal of impacted tooth, root ,root tips that are deep in the bone which is near the nerve.

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2.During nerve block (deep dental injection) of IAN & mental nerve.

3.While creating incision extend to mental foramen and lingual vestibular

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4.during perforation and fracture of lingual cortical plate during sectioning of the roots and crown of impacted 3 rd molars.

5.When the bur enters the

mandibular canal during sectioning.

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6.During displacement of a root tip inside the

mandibular canal during extraction attempt.

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7.During excessive flap retraction

8. When the bone near the nerve is excessively heated, if the surgical

handpiece is used with out a coolant(water or saline solution)

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9.During cleansing of a

periapical lesion,of

posterior teeth that are in direct contact with or near the mandibular canal.

10.During implant placement.

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Neuro physiology post injury

Compression

: Nerve compression may result in a neuropathic pain syndrome or sensory deficit. The mechanism includes mechanical deforming forces and ischemic changes.Compartment syndrome: similar to nerve compression but due to ischemia caused by diminished flow-decreased oxygen flow to the nerve.

The reversibility is depend on how much and how long pressure is applied.

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Stretch injury

: Injury following stretch or traction . Complete cessation in arterial blood flow occurred with 15% elongation. Injuries to the lingual nerve from laryngoscope, intubation , jaw retraction have postulated stretching mechanism.

Chemical injury: some chemicals such as neural sensitization are used which implicate nerve injury.Nerve injection injury in removal of tooth.

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PREDISPOSING FACTORS

Nerve location

– close proximity of the lingual nerve to the cortex of the mandible may cause entrapment.Hormonal changes in some cases;females

–there was a greater chance that those with estrogen and than those without it.

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Genetics

- still no direct evidence of a genetic predisposition for nerve injury, the recovery and resultant pain may have a genetic base.

Ref : Lingual nerve injury headache-The Journal of head and neck pain-2003;43:975-983

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SIGNS & SYMPTOMS

Numbness or pain in the chin, lip, tongue

Tingling or electric shock sensationImpaired speechLoss of tasteAbnormal chewingBiting of tongue and lipsBurning sensation

Paralysis(bell’s palsy)

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EXAMINATION

Includes detailed history,

behavioral assesment , physical examination.Special sensory tasting may be donePalpation over the injury site may produce local sensitivity or an evoked sensation in the tongue.

Taste testing may be performed but difficult to obtain accurate response.

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IMAGING

Ultra sound guidance enables the for proper visualization of the nerve.

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TREATMENT

Treated by

1.Non surgical 2.Surgical 3.Behavioral strategiesNon surgical:

cortico steriods -to reduce immune inflammatory reation.

Topical application: Capsaicin applied regularly will result in desensitization and pain relief(5 times per day for 5 days)

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4%

lignocaine or EMLA is useful if the patient cannot withstand the burning sensation.

Clonidine can be applied to hyperalgesic region by placing the patch where it is tender.An acrylic stent is manufactured to cover the painful site.Topical

clonazepam(0.5 to 1.0mg 3 times per day) to reduce oral burning pain.Tricyclic antidpressant

- Amitriptyline- effective in traumatic neuralgia.

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BEHVIORAL STRATEGIES

Before beginning, it is common to perform a

behavioral assessment with appropriate testing. The factors are: 1.Behavioral or operant 2.emotional

3.characterlogical 4.cognitive 5.side effects 6.medications use

7.compliance

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SURGICAL

Micro surgical techniques for nerve repair

Repair may entail decompression , direct suture or graftingExcision and apposition with suture was the effective repair procedure.Micro decompression is very effective in the compression neuropathies.

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Management of lingual nerve injury:

REMOVAL OF LOWER THIRD MOLAR

Division of lingual nerve noted at operation Immediate micro surgical repair

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POST OPERATIVE VIEW:

Stimulus evoked anaesthesia(

surgi- paresthesia cal intervention) Monitor recovery1.light touch

2.pin prick 3.two point disc-

rimnation

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3 months after injury

Some recovery no evidence

of recoveryContinue to monitor.

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MICRO NEURO SURGERY

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1.To minimize the risk of Lingual nerve injury , the standard TERENCE WARD’S INCISION was made in all cases.

2.After reflecting the buccal flap , a gutter in the disto buccal

bone was created to expose maximum contour of the tooth.

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CASE REPORT

A 34 year old patient with no medical history was subjected to

thrid molar removal in the 4 th quadrant( disto angular impaction).Before the procedure, IANB and sub mucosal infiltration of

buccal nerve given.For proper exposure, standard ward’s incision , gutter in the distobuccal bone was made.

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Further , distal

osteotomy and a lingual flap elevation without retraction. To close the wound 3-0 silk was used.

During the immediate post operative period, the patient had a pain and swelling limited to right paramandibular region.It was reduced with oral NSAID(Ibuprofen).One week after , patient reported with altered taste of anterior two third of right hemi tongue.

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During physical examination, UNILATERAL ATROPHY OF FUNGIFORM PAPILLAE at anterior two third of tongue and signs of recent bites noted.

Difficulty of diction also present.

1 st week after third molar removal:

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After a further follow up at 6 months, patient had a great improvement in

somatosensory symptoms. On examination, decrease in atrophy of papillae was shown.

Conclusion was made that, lingual nerve injury may be temporary or permanent. persistence of papillae atrophy is an important indicator of nerve injury . This usually improves within 6 months.

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The lack of recovery within this period of time – beyond two years is the bad prognosis.

In such cases, drug treatment –tricyclic

antidepressant may be given.Microsurgical reconstruction can be made in permanent injuries.References:Lingual nerve injury after third molar removal- J Clin

Exp Dent. 2014;6(2):e193 – e196.

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thank you!